The present application relates to radiation systems. It finds particular application in the context of security imaging, where it may be desirable to display high resolution projection images representative of an object to security personnel while utilizing volumetric data representative of the object for automated threat detection. However, it may also find applicability in medical fields, industrial fields, and/or other fields where radiation systems are employed to examine/image an object.
Today, radiation systems (e.g., also referred to as imaging systems) such as computed tomography (CT) systems, single-photon emission computed tomography (SPECT) systems, projection systems, and/or line systems, for example, are useful to provide information, or images, of interior aspects of an object under examination. Generally, the object is exposed to radiation comprising photons (e.g., such as x-rays, gamma rays, etc.), and an image(s) is formed based upon the radiation absorbed and/or attenuated by interior aspects of the object, or rather an amount of photons that is able to pass through the object. Generally, highly dense aspects of the object absorb and/or attenuate more radiation than less dense aspects, and thus an aspect having a higher density, such as a bone or metal, for example, may be apparent when surrounded by less dense aspects, such as muscle or clothing.
Radiation systems are utilized in a variety of fields to image/examine aspects of an object not readily visible to the naked eye. For example, radiation systems are used in security applications to identify potential threat items, which may include weapons and/or explosives, concealed within a suitcase, bag, or person, for example. Two of the more commonly used radiation systems in security applications are CT systems and line-scan (or line) systems (e.g., or projection systems). Line systems are configured to view the object from a limited number of angles and generate projection images (e.g., two dimensional images) respectively representing a collapsed or flattened, two-dimensional view of the object (e.g., where the densities of aspects of an object through a line in which radiation travels are integrated and represented as a single point on the image). Such systems are particularly valuable for generating high resolution 2D images for display to security personnel responsible for identifying potential threat objects.
CT systems are configured to view an object from a plurality of angles (e.g., at least 180 degrees but often 360 degrees) and to generate volumetric data representative of the object. In this way, a 3D model of the object can be created and properties of respective aspects within the object, such as density information, z-effective information, shape characteristics, etc. can be determined. Using one or more of these properties, automated threat analysis can be performed to determine if the object is a potential threat item. Moreover, two-dimensional or three-dimensional images can be obtained from CT systems that are representative of the object (e.g., although typically such images are of a lower resolution than the projection images generated by line scanners due to differences in the resolution of CT detector arrays relative to detector arrays utilized in line and/or projection systems).
While automatic threat analysis algorithms have proven useful, such algorithms may, at times, mischaracterize an object, resulting in a false positive. In a security application this may result in non-threat objects being incorrectly classified as potential threats. Accordingly, items flagged as potential threat items may have to be resolved by some other method(s), such as a visual inspection of image(s), hand search of the items, and/or via use of some other screening technology.